If you’re referring to a certain passage in Hebrews, I think that’s a widely misinterpreted passage. It’s saying to backsliding believers that while you’re moving backwards, you cannot also be moving forwards. Its scope is small scale and not permanent, as following the narrative makes clear.
You might subscribe to the false proverb that you can't judge a book by its cover, but you indeed can in the spiritual realm.
I see people who have spit in God's face by mutilating their bodies beyond remedy, and I have a pretty good idea that they will never repent, nor have that ability.